P. Fort et al., AFFERENTS TO THE NUCLEUS-RETICULARIS PARVICELLULARIS OF THE CAT MEDULLA-OBLONGATA - A TRACT-TRACING STUDY WITH CHOLERA-TOXIN B-SUBUNIT, Journal of comparative neurology, 342(4), 1994, pp. 603-618
The aim of this study was to examine anatomical evidence in cats of wh
ether the nucleus reticularis parvicellularis (Pc) is part of the circ
uit responsiblefor the inhibition of brainstem motoneurons during para
doxical sleep. For this purpose, we made iontophoretic injections of t
he retrograde and anterograde tracer cholera toxin B subunit (CTb) in
the Pc. After CTb injections in the Pc, a large number of retrogradely
labeled neurons were seen in the central nucleus of the amygdala, the
lateral part of the bed nucleus of the stria terminalis, the posterio
r hypothalamic areas, the mesencephalic reticular formation, the nucle
us locus subcoeruleus, the nucleus pontis caudalis, other portions of
the Pc, the nucleus reticularis dorsalis, the trigeminal sensory compl
ex, and the nucleus of the solitary tract. We further found that the P
c receives 1) serotoninergic afferents from the raphe dorsalis,magnus,
and obscurus nuclei; 2) noradrenergic inputs from the dorsolateral po
ntine tegmentum; 3) cholinergic afferents from the lateral medullary r
eticularformation; 4) substance P-like afferents from the central nucl
eus of the amygdala, bed nucleus of the stria terminalis, periaqueduct
al gray, and nucleus ofthe solitary tract; and 5) methionine-enkephali
n-like projections from the periaqueductal gray, the nucleus of the so
litary tract, the lateral pontine and medullary reticular formation, a
nd the spinal trigeminal nucleus. We further found that the Pc do not
receive afferents from brainstem structures responsible for muscle ato
nia, such as the ventromedial medulla and the dorsomedial pontine tegm
entum, and therefore may not be part of the circuit inhibiting the bra
instem motoneurons during paradoxical sleep. (C) 1994 Wiley-Liss, Inc.